For context, Victor Mair is a leading figure in Chinese history and linguistics. Recently there has been a raft of interesting re-interpretations by academics outside of China (in this case Taiwan) chipping away at the modern mythology of a unified Chinese history which is overtly pushed by Beijing against the scientific findings of academics, who in China are pressured not to publish materials revealing complex intercultural or non-Chinese heritage in border regions (source: personal statements by actual academics, 20+ years in the country).

For example, in the southwest we have seen the term China itself come under reconsideration by other respected linguists as a term potentially utilised by India to refer to a tribal federation in the Yunnan-Guizhou-Guanxi area known as Yelang. https://en.wikipedia.org/wiki/Yelang https://en.wikipedia.org/wiki/Names_of_China#Names_in_non-Ch...

Further, mtDNA evidence has confirmed matrilineal migration from India/Myanmar toward Yunnan and Sichuan that does not fit with the official narrative of 'civilisation came from north China and spread south' (my paraphrasing).

The precise origin of rice agriculture, the foundational technology of Asian civilisation, is hotly debated, but only within river systems effectively encircling southwest China which therefore was likely a major conduit through which such technology was shared (India, China, Southeast Asia inclusive), a situation that is not well researched for political reasons.

Art history however confirms interesting things like the fact that stilt houses (such as are popular in tropical regions of Asia and frequently co-occuring with intensive rice agriculture which effectively allowed and defined high population density and thus power-projection capable Asian civilisations) were first documented on stone carvings in tombs of Sichuan and evidence currently supports the spread of the same southward along with other technologies (such as lacquerware) roughly concurrent to the defeat of the Shu kingdom of Sichuan by the Han (~316BCE). https://en.wikipedia.org/wiki/Shu_(kingdom)

It also confirms much later significant overland connections (~1000CE) from the Pala Kingdom of Bengal with the Nanzhao Kingdom of Yunnan for example through stone carved Hindu grottoes. (See also https://en.wikipedia.org/wiki/M%E1%BB%B9_S%C6%A1n for a well evidenced nautical thrust of Indic culture on China's doorstep)

What is often misunderstood by casual historians is the extent to which the premodern area was wild jungle. A partial translation of mine goes some way to explaining the situation ~1000CE at https://en.wikibooks.org/wiki/Manshu/Chapter_7 but earlier situations are hinted at through the flowery language of the Shanhaijing (Classic of Mountains and Seas) which effectively asserts much of the Sichuan basin to be uninhibited tropical jungle with elephants, tigers, dense vegetation and bird life.

Short version: We know only a little about what actually happened in border regions, but it's more important and more complex than people give it credit for, largely due to recent political meddling and socio-historical quirks affecting academic focii. Every instance of academic inquiry in to our shared heritage in this area deserves to be supported. On the Persian note, few people recognise the prior significance of Farsi in regional diplomacy, that muslims in western China derive their religious vocabulary from the Persian tradition, or that Zheng He (much lauded nautical explorer of Southeast Asia and Africa in the Ming Dynasty) was a eunuch culled from the abortive Muslim dynastic ruling family of Southwest China descended from the Emir of Bukhara in Turkmenistan who had accompanied the Mongol Horde on their conquering of China to usher in the Yuan Dynasty. Ahh yes, Chinese history. Not so Chinese after all.